1. Field of the Invention
The present invention relates to a server that provides a plurality of types of content to another device and a method for controlling the server.
2. Description of the Related Art
In wireless local area network (LAN) standards corresponding to the Institute of Electrical and Electronics Engineers (IEEE) 802.11, the infrastructure mode and the ad-hoc mode are provided. In the infrastructure mode, stations (STAs) communicate with each other under the control of an access point (AP). In the ad-hoc mode, STAs communicate with each other without control by an AP.
A technique for performing switching between the infrastructure mode and the ad-hoc mode is disclosed in United States Patent Application 20040063458 (Japanese Patent Laid-Open No. 2004-128785), in which communication is started in the infrastructure mode, and the communication mode is changed to the ad-hoc mode when STAs are in an environment in which the STAs can communicate with each other without the intervention of an AP.
However, a problem exists in that, when a repeater, such as an AP, relays communications between wireless terminals and a wired network, the communication mode cannot be readily switched between the infrastructure mode and the ad-hoc mode. For example, when, in addition to communications via an AP, communications with a terminal in a wired network are performed, the communication mode cannot be automatically changed to the ad-hoc mode.
Moreover, another problem exists in that transmission of communication data suitable for the nature of the communication data cannot be made merely by changing the communication mode from the infrastructure mode to the ad-hoc mode. These problems will now be described in detail.
In the IEEE 802.11e standard, a hybrid coordinator is defined. A hybrid coordinator sets an enhanced distributed channel access (EDCA) parameter set in response to the status of a transmission line and sends the EDCA parameter set to terminals in the form of a beacon and the like. An EDCA parameter set includes quality of service (QoS) information, such as the acknowledgement policy, and four parameters defined for individual access categories.
A first parameter is an arbitration interframe space number (AIFSN) that is the number of frames that are deferred for adjustment after detecting that no carrier exists before sending radio waves. A second parameter is CWmin, and a third parameter is CWmax (CW is an abbreviation for contention window that determines the window width for controlling contention). A fourth parameter is TXOP limit (the maximum time during which a transmission opportunity is continuously given).